[Nexthop] Add FBOSS-OSS Kernel

Summary:

Here an RPM specfile and surrounding machinery is added to build an
FBOSS-compatible Linux kernel from vanilla Linux sources which is
compatible with CentOS. On top of this reference configuration,
additional local changes from `fboss-local-overrides.yaml` are applied
prior to building.

To use, inside an FBOSS build container, run:

    # fboss-image/kernel/scripts/build_kernel.sh 6.4.3 out
    ...
    Kernel RPM build complete!
    Output files:
    out/x86_64/kernel-modules-6.4.3-1.fboss.el9.x86_64.rpm
    out/x86_64/kernel-headers-6.4.3-1.fboss.el9.x86_64.rpm
    out/x86_64/kernel-core-6.4.3-1.fboss.el9.x86_64.rpm
    out/x86_64/kernel-devel-6.4.3-1.fboss.el9.x86_64.rpm
    out/BUILD/linux-6.4.3/kernel/config_data.gz
    out/SRPMS/kernel-6.4.3-1.fboss.el9.src.rpm
    out/kernel-6.4.3.rpms.tar.gz
    out/kernel-6.4.3-1.fboss.el9.src.rpm
    out/RPMS/x86_64/kernel-modules-6.4.3-1.fboss.el9.x86_64.rpm
    out/RPMS/x86_64/kernel-headers-6.4.3-1.fboss.el9.x86_64.rpm
    out/RPMS/x86_64/kernel-core-6.4.3-1.fboss.el9.x86_64.rpm
    out/RPMS/x86_64/kernel-devel-6.4.3-1.fboss.el9.x86_64.rpm
    # ls fboss-image/kernel/dist/build-6.4.3/out/
    kernel-6.4.3-1.fboss.el9.src.rpm  kernel-core-6.4.3-1.fboss.el9.x86_64.rpm   kernel-headers-6.4.3-1.fboss.el9.x86_64.rpm
    kernel-6.4.3.rpms.tar.gz          kernel-devel-6.4.3-1.fboss.el9.x86_64.rpm  kernel-modules-6.4.3-1.fboss.el9.x86_64.rpm

Author: raghav-nexthop

fboss-image/kernel/configs/fboss-local-overrides.yaml

@@ -0,0 +1,51 @@
+# FBOSS Local Configuration Overrides
+#
+# Copyright (c) 2004-present, Facebook, Inc.
+# All rights reserved.
+#
+# This source code is licensed under the BSD-style license found in the
+# LICENSE file in the root directory of this source tree. An additional grant
+# of patent rights can be found in the PATENTS file in the same directory.
+#
+# This file contains local overrides to the Meta fboss-reference.config
+# organized by common settings and kernel version-specific settings
+
+# Common overrides that apply to all kernel versions
+# Add config lines here
+common_overrides: |
+  # These changes disable settings in Meta reference config that don't exist in standard linux source
+  CONFIG_BOOT_CONFIG_EMBED_FILE=""
+  CONFIG_SYSTEM_TRUSTED_KEYS=""
+
+  # Drivers for Golden Eagle platform
+  CONFIG_EEPROM_AT24=m
+  CONFIG_SENSORS_TMP464=m
+  CONFIG_SENSORS_LM90=m
+  CONFIG_SENSORS_PMBUS=m
+  CONFIG_SENSORS_ADM1266=m
+  CONFIG_SENSORS_ISL68137=m
+  CONFIG_AD525X_DPOT=m
+  CONFIG_AD525X_DPOT_I2C=m
+  CONFIG_NET_VENDOR_AMD=y
+  CONFIG_AMD_XGBE=m
+  CONFIG_AMD_XGBE_DCB=y
+  CONFIG_AMD_XGBE_HAVE_ECC=y
+  CONFIG_X86_AMD_PLATFORM_DEVICE=y
+  CONFIG_I2C_DESIGNWARE_PLATFORM=y
+  CONFIG_I2C_DESIGNWARE_PCI=y
+  CONFIG_ACPI_SPCR_TABLE=y
+  CONFIG_SERIAL_8250_DW=m
+  CONFIG_SERIAL_8250_DWLIB=m
+  CONFIG_SERIAL_8250_PNP=y
+
+
+# Kernel version overrides
+# Add kernel version as key, then add config lines in the value
+kernel_version_overrides:
+  "6.4.3": |
+    # Specific overrides for kernel 6.4.3
+    # Add any 6.4.3-specific config lines here
+
+  "6.11.1": |
+    # Specific overrides for kernel 6.11.1
+    # Add any 6.11.1-specific config lines here